Conservation Genetics

Human population growth and expansion have led to the
restriction of many wildlife species on a small portion of their
historic ranges. Wide-ranging mammals are particularly susceptible
to range contractions, since even large parcels of land may only
support small populations. In North America, wide-ranging mammals
such as black bear, caribou, elk, grizzly bear, and pronghorn have
lost up to 74% of their historic range over the past 150 years.
Precious few examples exist of reintroduction programs which are
considered successful in both ecological and genetic terms. Some of
the most widely cited examples of successful reintroduction
programs, such as the Alpine ibex, have resulted in populations
with comparatively low levels of genetic diversity. Genetic
diversity is the "currency" of evolution, as it allows species to
adapt to environmental change. Conversely, low levels of genetic
diversity are associated with increased extinction rates. A major
focus of my research is understanding how we can manage wildlife
species in discontinuous populations to best promote long-term
conservation.

American bison as a model species

Private and government activists in the late 19th and early 20th
centuries successfully prevented the imminent extinction of the
American bison (Bison bison). The effort is considered one
of the first examples of a concerted conservation movement to save
a species. Nearly all modern bison populations are derived from the
lineages represented in publicly-maintained populations (state and
federal herds in Canada and the US), most of which contain genetic
evidence of historic hybridization with domestic cattle. As such,
the preservation of those populations free of domestic cattle
introgression is of paramount importance in the long-term
conservation of the bison species. Long-term preservation of
genetic integrity in these small, closed public populations,
however, requires intensive and continuous genetic management.
Recently, we examined the distribution of genetic variation within
and among U. S. federal bison populations and evaluated the effects
of various management strategies on genetic variability. Through
continued monitoring and appropriate management actions, changes in
genetic diversity can be assessed over time to ensure the long-term
genetic conservation of North American bison.